Question

A sample of an unknown substance has a mass of 89.5 g. If 345.2 J of heat are required to heat the substance from 285 K to 305 K, what is the specific heat of the substance?

Answer 1

The specific heat of a substance can be found using the formula q = mcΔT, where q is the heat energy added, m is the mass, and ΔT is the change in temperature. For the given substance, the specific heat is calculated to be 0.193 J/g°C.

Step-by-step explanation:

Finding the Specific Heat of a Substance

To determine the specific heat (c) of a substance, we use the formula:

q = mcΔT

where:

• q is the heat energy (in joules, J)
• m is the mass of the substance (in grams, g)
• ΔT is the change in temperature (in Kelvins, K or degrees Celsius, °C)

In this case, we have:

• q = 345.2 J
• m = 89.5 g
• ΔT = 305 K - 285 K = 20 K

Plugging these values into the formula gives us:

c = q / (mΔT) = 345.2 J / (89.5 g * 20 K)

After calculating, the specific heat c turns out to be:

c = 0.193 J/g°C

This value can then be used to compare with Table 9.1 to guess the unknown substance's likely identity if it matches any listed specific heat values.

Answer 2

The specific heat is the heat needed per unit mass to raise the temperature by 1 degree celsius. So the specific heat = heat/(mass*ΔT) = 345.2/[89.5*(305-285)]=0.193 J/(g*℃). When using ΔT, the unit K and ℃ are the same.